Tow conveyor

ABSTRACT

A tow conveyor includes at least one carrier. Connected to the front and rear of the carrier are rod members extending forwardly downward and rearwardly downward respectively and pivotally movable in horizontal and vertical directions. Running assemblies free to move on guide rails are connected to the lower ends of the rod members respectively so as to be pivotally movable in horizontal and vertical directions. The front running assembly has an engaging dog projecting downward and the rear running assembly has a horizontal tilting plate. A trolley driven on endless rails has pivoted thereto a pusher engageable with the engaging dog and tilting dogs to be pivotally forced down by the tilting plate on the rear running assembly of a preceding carrier to thereby tilt the pusher through a link when the carrier approaches the preceding carrier.

United States Patent 1 Wakabayashi [30] Foreign Application PriorityData July 10, 1972 Japan 47-69295 [52] U.S. Cl 104/170; 104/172 B;104/172 5 [51] Int. Cl B61b 13/00 [58] Field of Search 104/172 B, 172 C,172 BT, 104/172 S, 170,148 LM [56] References Cited UNITED STATESPATENTS 3,099,228 7/1963 Lingg 104/172 S 3,518,946 7/1970 Kavieff104/172 B 3,548,751 12/1970 lzhelya et a1 104/148 LM [451 May 13, 1975Primary Examiner-Evon C. Blunk Assistant ExaminerRobert Saifer Attorney,Agent, or FirmArmstrong, Nikaido & Wegner [57] ABSTRACT A tow conveyorincludes at least one carrier. Connected to the front and rear of thecarrier are rod members extending forwardly downward and rearwardlydownward respectively and pivotally movable in horizontal and verticaldirections. Running assemblies free to move on guide rails are connectedto the lower ends of the rod members respectively so as to be pivotallymovable in horizontal and vertical directions. The from running assemblyhas an engaging dog projecting downward and the rear running assemblyhas a horizontal tilting plate. A trolley driven on endless rails haspivoted thereto a pusher engageable with the engaging dog and tiltingdogs to be pivotally forced down by the tilting plate on the rearrunning assembly of a preceding carrier to thereby tilt the pusherthrough a link when the carrier approaches the preceding carrier.

6 Claims, 20 Drawing Figures PATENIEDHAY13I975 3.882.793

SHEEI 2 OF 7 FIGJ.

PATENTED HAY I 3 I975 SHEET 3 OF 7 Q'j Bl-IIIIIII-IIIIII PATENTED MAY 13 I975 SHEET 1 SF 7 FIG.

PATENTED MAY 1 3:975 3. 882 793 saw 5 or 7 FIG. 11

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TOW CONVEYOR BACKGROUND AND SUMMARY This inventionrelates to a towconveyor, more particularly to a c'onve'yor'having a mechanism foreffecting engagemeiitand disengagement between a carrier and apropelling pusher.

I Conventional "tow conveyors include those adapted to turn within avertical plane and those turnable within a horizontal plane. The formerare usable only for rectilinear transport, while the latter are somewhatadapted for three-dimensional transport but are not fully operable alonga bent or flexed track unlike a trolley conveyor. The tow conveyor ofthis invention assures satisfactorythree-dimensional transport asachieved by the trolley conveyor. Further with the present conveyor, arequired number of carriers can be accumulated as desired not only at astraight portion of the conveyor line but also at curved portionsincluded in horizontal and vertical planes. When the carrier is moved bya pusher from an accumulated position, the engagement of the pusher withthe carrier is always assured even if a trolley equipped with the pusheris driven at a high speed. Although the carrier of this conveyor hasmovable engaging and disengaging means for the above-mentionedaccumulation, the means can be fixed to the carrier to render thecarrier usable also as a hand-operated vehicle.

The invention will be described below in detail with reference to theaccompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing an embodimentof the conveyor according to this invention and having a conveyor lineof the circulating type constructed in a horizontal plane;

FIG. 2 is a side elevation of the conveyor of FIG. 1 with part of railsbroken away;

FIG. 3 is an enlarged view in section taken along the line III-III inFIG. 2;

FIG. 4 is an enlarged side elevation showing a front running assemblyhaving an engaging dog;

FIG. 5 is a view in section taken along the line VV in FIG. 4;

FIG. 6 is an enlarged side elevation showing a rear running assemblyhaving a tilting plate;

FIG. 7 is a view in section taken along the line VII- VII in FIG. 6;

FIG. 8 is an enlarged plan view showing a trolley having a pusher anddogs for tilting the pusher;

FIG. 9 is side elevation of the trolley of FIG. 8;

FIGS. 10 to 13 are schematic side elevations showing accumulation ofcarriers in sequential order;

FIGS. 14. and are side elevations of the conveyor of this invention atascending and descending portions of the conveyor line;

FIG..16 is a plan view showing a loop of endless conveyorlineandstraight conveyor lines branching off the loop for guiding the carriersinto or out from the loop; FIG. 17 is a side elevation in sectionshowing a device for fixingthe rod member of the carrier;

. FIG. 18 is a view in section taken along the line XVIII XVIII in FIG.17;

FIG. 19 is a view in section showing a modified device for fixing therod member of the carrier and corresponding to FIG. 18; and

FIG. 20 is a view taken along the line XX-XX in FIG. 19.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS With reference to FIGS. 1 to 9and FIG. 17, a loop of endless belt conveyor line 1 comprises first,second and third rails 2, 3 and 4. Each pair of the first and secondrails 2 and 3 is composed ofa pair of steel members laterally U-shapedin section. The second rails 3 are placed on the first rails 2, and therails 3 and 2 are supported on a number of support members 6 spacedapart by a specified distance on the floor 5 and are positioned abovethe floor 5 in proximity thereto. The third rails 4 are made of a pairof U-shaped steel members which are disposed on the floor 5 at theopposite sides of the first and second rails 2 and 3.

A carrier 7 is in the form of a framein its entirety and has front andrear elevated flat portions 8. The carrier 7 includes front and reartransverse beams 9 provided close to their opposite ends withhorizontally rollable wheels 26 in contact with the third rails 4. Thecarrier 7 is therefore guided by the third rails 4. Fixed to the outerface of each transverse beam 9 at the midportion of its length is alaterally U-shaped connecting member 25 to which is connected by a pin11 a cylindrical portion 10a formed at one end of a short upperconnector 10, the connector being horizontally pivotable. A plateportion 1012 at the outer end of the connector 10 is loosely fitted in,and connected by a pin 13 to, a bifurcated end 12a of an elongated rodmember 12 which is also bifurcated at the other end 1212. Thus the rodmember 12 is pivotally movable in vertical directions (see FIG. 17).Connected respectively to the lower ends of the rod members 12 are frontand rear running assemblies 14 and 15 guided by the second rails 3. Eachof the running assemblies 14 and 15 includes an inverted U-shaped body16, front and rear pairs of verti cal rollers 17 disposed at the leftand right sidesof the body 16 in rolling contact with the lower faces ofthe second rails 3, a pair of front and rear horizontal rollers 18disposed on the upper surface of the body 16, an upper plate 19 having ahorizontal edge 19a projecting toward the carrier and a pin 20 extendingvertically through the upper plate 19 and fixed thereto, with one of thehorizontal rollers 18 mounted on the downwardly projecting portion ofthe pin 20. A cylindrical portion 21a formed at one end of a short lowerconnector 21 is mounted on the pin 20 in a horizontally pivotablemanner. A plate portion 21b at the other end of the connector 21 isloosely fitted in, and connected by a pin 22 to, the lower bifurcatedend 12b of the rod member 12. Accordingly, the running assemblies 14 and15 are pivotally movable in vertical directions. Fixedly fitted in thefront end of the body 16 of the front running assembly 14 is part of anengaging dog 23 which is T-shaped as seen from the front. The dog 23 hasa lower end which coincides with the under faces of the second rails 3and a rear slanting portion 23a. Extending over the lower end of thebody 16 of the rear running assembly 15 is a horizontal tilting plate24, part of which is fitted in and fixed to the lower end. The under endface of the plate 24 is positioned substantially at the same level asthe under faces of the second rails 3. Slanting portions 24a are formedat the front and rear ends of the tilting plate 24 respectively.

An endless chain 27 is reeved around a drive sprocket wheel to be drivenby an unillustrated motor and a driven sprocket wheel and is coextensivewith the conveyor line 1.

A trolley 28 comprises a body 32 made of a pair of side plates securedto an upright member 30 fixed at left and right to the upper surface ofa link of the chain 27 and spaced apart by a specified distance with aspacer 31 extending between the upper ends of the side platesapproximately at the middle of their length, trolley rollers 33 disposedat the opposite sides of the body 32 in rolling contact with the lowerfaces of the first rails 2, a pusher 35 tiltably supported on a pivot 34at an upper rear end portion of the body 32, two pusher tilting dogs 36tiltably mounted on a pivot 38 at a midportion of front end of the body32 with a spacer 37 interposed therebetween, two links 39 connecting thetwo dogs 36 to the pusher 35 and a reverse travel preventing dog 41interposed between the two dogs 36 and tiltably supported thereon by apivot 40. Normally, the pusher 35, pusher tilting dogs 36 and reversetravel preventing dog 41 remain in upright position by virtue of theweight of portions thereof lower than the pivots 34, 38 and 40, withtheir upper ends projecting between the second rails 3. The pusher 35and dogs 36 are provided, at inner faces of their lower ends, withstoppers 44 and 45. The front ends of the links 39 are connected to thepusher tilting dogs 36 by a pin 42 positioned above the pivot 38. Therear ends 39b of the links 39 are pivotally connected to the pusher 35by a pin 43 positioned at a lower level than the pivot 34. The spacebetween the two parallel pusher tilting dogs 36 is greater than thewidth of the engaging dog 23 but smaller than the width of the tiltingplate 24.

As shown in FIG. 2, the carrier 7 is driven leftward in the drawingalong with the drive chain 27 by engagement of the pusher 35 of thetrolley 28 with the engaging dog 23 of the running assembly 14 connectedto the rod member 12. Although not shown, a number of carriers followthe carrier 7 at specified spacing that is determined by the spacing ofthe trolleys 28 on the chain 27, therefore by the spacing of the pusher35.

A number of carriers travelling in a continuous fashion will beaccumulated at a specified position in the manner described below withreference to FIGS. to 13. A first carrier 7A (FIG. 10) is travellingwith a trolley 28 by virtue of engagement with the pusher 35 asdescribed above. A stopper (not shown) which is adapted to project intoand retract from the path of travel of the upper portions of the pushertilting dogs 36 on the trolley 28 projects into the path, upon contactwith which the dogs 26 incline backward. This movement is transmittedthrough the links 39 to the pusher 35, which is therefore inclinedforward and disengaged from the engaging dog 23. Consequently, the firstcarrier 7A is brought out of connection with the travelling trolley 28and stopped. By the term first carrier herein referred to is meant thefirst of a number of the travelling carriers to be stopped. When thefirst carrier 7A is brought to a halt in this way, the second andfollowing carriers are still travelling along with the drive chain 27.As the second carrier 7B approaches the first carrier 7A which hasalready been stopped, the pusher tilting dogs 36 of the trolley 28connected to the second carrier 78 come into contact with the tiltingplate 24 of the rear running assembly of the first carrier 7A (see FIG.11). As the trolley 28 further advances, the dogs 36 are inclined by thetilting plate 24 in its stopped position, with the result that thepusher 35 is also inclined as described above and disengaged from theengaging dog 23. Thus the second carrier 7B is also brought to a halt(see FIG. 12). The dogs 36, reverse travel preventing dog 41 and pusher35 pass under the tilting plate 24 in inclined state, whereupon they arebrought to the original upright position by gravity (FIG. 13). When thedogs 36, 41 and pusher 35 reach the position of the engaging dog 23 ofthe front running assembly 14 of the first carrier 7A, the stopperpositioned in front of the engaging dog 23 inclines the dogs 36, 41first and then pusher 35, permitting the same to pass under the engagingdog 23 free of trouble. The drive chain 27 continues to travel, and thethird and following carriers are brought to a halt in like manner insuccession, each adjacent the preceding one.

To travel the group of stopped carriers, the stopper halting the firstcarrier 7A is removed from the path of travel of the tilting dogs 36.This permits a pusher 35 advancing from behind the carrier on thetravelling chain 27 to come into engagement with the engaging dog 23 ofthe front running assembly 24. Thus the first carrier 7A starts toadvance along with the drive chain 27. By virtue of advance of the firstcarrier 7A, the rear running assembly 15 of the first carrier 7Apositioned in proximity to the front running assembly 14 of the secondcarrier 78 moves away, permitting a following pusher 35 to remainupright and come into engagement with the engaging dog 23 of the secondcarrier 78. This advances the carrier 78. Similarly, the stoppedcarriers are initiated into forward travel in succession at an intervalcorresponding to the distance between the pushers 35.

According to the construction described, it is impor tant to provide twoparallel pusher tilting dogs 36 which are spaced apart by a distancegreater than the width of the engaging dog 23 but smaller than the widthof the tilting plate 24. If only one dog 36 is provided in opposingrelation to the pusher 35, the dog 36 which approaches the engaging dog23 earlier than the pusher 35 and strikes the dog 23 first would beinclined when the carrier 7 is moved from the stopped position asdescribed above, consequently tilting the pusher 23 through the movementof the links 39. Since the dog 36 is designed to stand up upon passingunder the engaging dog 23, the pusher will also stand up but if thechain is driven at a high speed, the pusher 35 will pass under the dog23 before the pusher 35 returns to a level where it is engageable withthe dog 23. It would them be impossible to connect the carrier 7 to thetrolley 28 and the carrier 7 would remain stopped against travel. Sincesuch pivotal movement of the pusher 35 is effectd by the similarmovement of the tilting dog 36, the dog 36 need only be prevented fromtilting in such case. According to this invention, therefore, the twodogs 36 are adapted to move past the engaging dog 23 at its oppositesides, free of contact therewith (see FIG. 5).

It is noted that the front running assembly 14 having the engaging dog23 is pivotally movable in horizontal and vertical directions withrespect to the rod member 12, which in turn is pivotable in horizontaland vertical directions with respect to the carrier 7. Accordingly,throughout the horizontal portion of the loop of endless conveyor line 1part of which is shown in FIG. 1, ascending portion 1a (see FIG. 14) anddescending portion lb included in the line 1, the carrier 7 can betravelled three-dimensionally by the movement of the chain 27 which isflexible three-dimensionally, without permitting the disengagement ofthe pusher 35 from the engaging dog 23. Further inasmuch as the rearrunning assembly having the tilting plate 24 is connected to the carrier7 in the same manner as the front running assembly 14, both the runningassemblies 14 and 15 can be brought close to each other even in curvedportions in horizontal and vertical planes to assure accumulation.

Occasionally, it will be desired to remove the carrier 7 from the loopof the endless conveyor line 1 or, conversely, to place the carrier 7onto the line 1 or to use the removed carrier in the same manner as ahandoperated vehicle. This invention can fulfil such need. Referring toFIGS. 16 to 18, the loop of endless conveyor line 1 is provided, alongextensions from the opposing straight line portions, with a straightconveyor line 46 for removing the carrier and a straight conveyor line47 for guiding the carrier onto the loop. The straight conveyor line 46for removal includes a pair of front and rear pits 48 each of whichaccommodates a rod fixing device 49. Carrier stoppers 50 and 51 aredisposed to the rear of the points where the straight conveyor lines 46and 47 branch off the endless conveyor line 1, with respect to thedirection of advance of the vehicles. It is not necessarily needed forthe conveyor lines 1, 46 and 47 to be equipped with the third rails 4for guiding the carriers 7 but the carriers per se may be travelleddirectly on the surface of the floor 5. Since the carriers 7 are drivenmanually on the straight conveyor lines 46 and 47, these lines need notbe equipped with the drive chain 27. Accordingly, the conveyor lines 46and 47 do not have the first rails 2 for guiding the trolleys 28suspending the chain 27. On the conveyor lines 46 and 47, the secondrails 3, L-shaped in cross section, are positioned below the surface ofthe floor 5, namely below the third rails 4. At the position of the pits48, the rails 3 include segments 3a having a length capable ofsupporting the running assemblies 14 and 15. If it is desired totransfer a carrier 7 onto the straight conveyor 46, following carriersare stopped by the stopper 50 in the foregoing manner, and the carrier 7is manually transferred onto the conveyor line 46. If it is desired toplace an additional carrier 7 onto the conveyor line 1, an advancingcarrier and following carriers on the line 1 are stopped by the stopper51 and the additional carrier 7 is placed onto conveyor line 1 toprecede the stopped carriers.

Under each of the front and rear flat portions 8 of the carrier 7 at amidportion of width thereof, there is a space 63 for accommodating therod member, at one side ofwhich there is fixedly provided a short holder50 in the form ofa square tube. A square rod-like support member 51having a downward projection 51a at its one end is slidingly insertedinto the holder 50 in a transverse direction.

The rod member fixing device 49 comprises a stationary plate 53 securedto the upper end of a support frame 52, a hydraulic cylinder 54extending vertically from the under face of the stationary plate 53 andfixed thereto, a lift table 57 supported on the upper end of piston rod55 of the hydraulic cylinder which extends upward through the stationaryplate 53 and having guide rods 56 extending downward through thestationary plate 53 at opposite sides of the rod 55, a horizontalhydraulic cylinder 59 fixed to a support 58 supporting the segments 3aand secured to the upper face of the lift table 57 and a support memberengaging member 62 fixed to the end of the piston rod 60 of thehydraulic cylinder 59 and having a recess 61. Although FIGS. 17 to 19show the device for the rear running assembly 15 only, the device forthe front running assembly 14 also operates exactly in the same manneras will be described below. When a carrier 7 is placed onto the straightconveyor line 46 for removal with the running assembly 15 positioned onthe segments 3a, the hydraulic cylinder 54 is actuated to project itspiston rod and to thereby elevate the lift table 57 as indicated in thechain line, permitting the rod member 12 to pivotally move about the pin13. When the distal end of the rod member reaches the space 63 in thecarrier 7, the hydraulic cylinder 54 is brought out of operation to stopthe lift table 57. While the hydraulic cylinder 54 is in operation,another hydraulic cylinder 59 is also operated to project its piston rod60. Thus while being elevated along with the lift table 57, the engagingmember 62 is moved leftward in FIG. 18 to the extremity of itshorizontal and vertical movement, where the recess 61 comes intoengagement with the downward projection 51a of the support member 51 inits pulled-out position. Subsequently, the piston rod is retracted tomove the support member 51 rightward along with the engaging member 62as indicated in a chain line, whereby the support member 51 ispositioned beneath the rod member 12. The piston rod 55 is thereafterretracted to lower the lift table 57. At this time, the rail segments 3aseparate from the running assembly to descend with the lift table 57.Consequently, the rod member 12 is received by the support member 51 andis held to the carrier 7 and will not cause any trouble, so that thecarrier can be used as a hand-operated vehicle. To return the rod member12 and the running assembly to the original state, the foregoingprocedure is followed in the reverse manner.

FIGS. 19 and 20 show a modified device for fixing the rod member.According to this modification, the running assembly is supported,instead of receiving the rod member by the support member. Fixed to theflat portion 8 of the carrier 7 on the under face of its rear end aretwo U-shaped holders spaced apart by a distance slightly greater thanthe width of the running assembly 15. A plate-like support member 71,transversely received in the holders 70 in slidable manner, has downwardprojections 71a at its opposite ends and a cutout 71b formed in its rearportion toward one end thereof and corresponding to the horizontalprojecting edge 19a of upper plate 19 of the running assembly 15.

A horizontal hydraulic cylinder 73 having a piston rod 72 extendingtherethrough is fixedly mounted on the lift table 57. The piston rod 72carries at its opposite ends vertical horn-like engaging members 74 theinner faces of which are spaced apart by a distance coinciding with thelength of the support member 71. P0- sitioned slightly under the upperends of the engaging members 74 is a support rod 76 for a rail segment75 made of a U-shaped steel member, the support rod 76 being parallel tothe piston rod 72 and secured in position.

To fix the rod member 12 to the carrier 7, the lift table 57 is raised.At this time, the piston rod 72 and the support member 71 are positionedtoward the right as indicated in solid line in the drawings. When thelift table 57 is raised, the horizontal projecting edge 19a of therunning assembly 15 passes through the cutout 71b in the support member71 and is positioned thereabove, and the engaging members 74 engage theouter side faces of the downward projections 71a of the support member71. In this state the hydraulic cylinder 73 is operated to force thepiston rod 72 leftward, shifting the support member 71 leftward asindicated in the chain lines in the drawings and thereby displacing thecutout 71b from the position of the horizontal projecting edge 19a. Whenthe lift table 57 is lowered along with the rail segment 75, the supportmember 71 receives the horizontal edge 19a, whereby the rod member 12 isheld to the carrier 7.

What is claimed is:

l. A tow conveyor comprising the combination of at least one carrier,first rails disposed close to the floor, second rails disposed on thefirst rails in parallel thereto, an engaging means connected to thecarrier pivotally movable in the horizontal and vertical directions andhaving rollers in rolling contact with the second rails, at least onetrolley including rollers in rolling contact with the first rails, adrive means connected to the trolley to move the trolley along the firstrails, and a pusher mounted on the trolley for engagement with theengaging means and projecting upward from the first rails to connect thecarrier to the trolley and to thereby move the carrier along with thetrolley, wherein the engaging means is positioned in front of thecarrier and a disengaging means is provided in the rear of the carrier,the disengaging means being connected to the carrier pivotally movablein the horizontal and vertical directions and having rollers in rollingcontact with the second rails, the trolley further including a pushertilting dog mounted thereon in from of a pusher and projection upwardfrom the first rails to disengage the pusher from the engaging means bybeing pivotally forced down by the disengaging means of a precedingcarrier and to thereby separate the carrier from the trolley, and,wherein the pusher tilting dog and the pusher are tiltably supported bypivots on the trolley and normally remain upright by virtue of theweight of their portions below the pivots, the trolley including a linkhaving a front end pivoted to the pusher tilting dog at a position aboveits pivot and a rear end pivoted to the pusher at a position below itspivot.

2. A tow conveyor comprising the combination of at least one carrier,first rails disposed close to the floor, second rails disposed on thefirst rails in parallel thereto, an engaging means connected to thecarrier pivotally movable in the horizontal and vertical directions andhaving rollers in rolling contact with the second rails, at least onetrolley including rollers in rolling contact with the first rails adrive means connected to the trolley to move the trolley along the firstrails, and a pusher mounted on the trolley for engagement with theengaging means and projecting upward from the first rails to connect thecarrier to the trolley and to thereby move the carrier along with thetrolley, wherein the engaging means is positioned in front of thecarrier and a disengaging means is provided in the rear of the carrier,the disengaging means being connected to the carrier pivotally movablein the horizontal and vertical direction and having rollers in rollingcontact with the second rolls, the trolley further including a pushertilting dog mounted thereon in fron of a pusher and projecting upwardfrom the first rails to disengage the pusher from the engaging means bybeing pivotally forced down by the disengaging means of a precedingcarrier and to thereby separate the carrier from the trolley, whereinthe trolley has two parallel pusher tilting dogs spaced apart by adistance greater than the width of an engaging dog disposed at the lowerend of the engaging means and smaller than the width of a tilting platedisposed at the lower end of the disengaging means.

3. The tow conveyor as set forth in claim 2 wherein a reverse travelpreventing dog is interposed between the two pusher tilting dogs and istiltably supported by a pivot and normally remains upright by virtue ofweight of its portion below the pivot.

4. A tow conveyor comprising the combination of at least one carrier,first rails disposed close to the floor, second rails disposed on thefirst rails in parallel thereto, an engaging means connected to thecarrier pivotally movable in the horizontal and vertical directions andhaving rollers in rolling contact with the second rails, at least onetrolley including rollers in rolling contact with the first rails, adrive means connected to the trolley to move the trolley along the firstrails, and a pusher mounted on the trolley for engagement with theengaging means and projecting upward from the first rails to connect thecarrier to the trolley and to thereby move the carrier along with thetrolley, wherein the engaging means is positioned in front of thecarrier and a disengaging means is provided in the rear of the carrier,the disengaging means being connected to the carrier pivotally movablein the horizontal and vertical directions and having rollers in rollingcontact with the second rails, the trolley further including a pushertilting dog mounted thereon in front of a pusher and projecting upwardfrom the first rails to disengage the pusher from the engaging means bybeing pivotally forced down by the disengaging means of a precedingcarrier and to thereby separate the carrier from the trolley, and whichincludes a fixing means for holding the engaging means and thedisengaging means to the under face of the carrier, respectively.

5. The tow conveyor as set forth in claim 4 wherein the fixing meanscomprises a support member for supporting a rod member connecting arunning assembly to the carrier pivotally movably in vertical directionsand a holder secured to the under face of the carrier to hold thesupport member slidably.

6. The tow conveyor as set forth in claim 5 further comprising a loop ofendless conveyor line including the first rails and the second rails, astraight conveyor line branching off the endless conveyor line andincluding the second rails, and a lift table supporting a rail segmentand an engaging member for operating the support member, the railsegment forming part of the second rails in the straight conveyor lineand having a length corresponding at least to the length of the runningassembly.

1. A tow conveyor comprising the combination of at least one carrier,first rails disposed close to the floor, second rails disposed on thefirst rails in parallel thereto, an engaging means connected to thecarrier pivotally movable in the horizontal and vertical directions andhaving rollers in rolling contact with the second rails, at least onetrolley including rollers in rolling contact with the first rails, adrive means connected to the trolley to move the trolley along the firstrails, and a pusher mounted on the trolley for engagement with theengaging means and projecting upward from the first rails to connect thecarrier to the trolley and to thereby move the carrier along with thetrolley, wherein the engaging means is positioned in front of thecarrier and a disengaging means is provided in the rear of the carrier,the disengaging means being connected to the carrier pivotally movablein the horizontal and vertical directions and having rollers in rollingcontact with the second rails, the trolley further including a pushertilting dog mounted thereon in from of a pusher and projection upwardfrom the first rails to disengage the pusher from the engaging means bybeing pivotally forced down by the disengaging means of a precedingcarrier and to thereby separate the carrier from the trolley, and,wherein the pusher tilting dog and the pusher are tiltably supported bypivots on the trolley and normally remain upright by virtue of theweight of their portions below the pivots, the trolley including a linkhaving a front end pivoted to the pusher tilting dog at a position aboveits pivot and a rear end pivoted to the pusher at a position below itspivot.
 2. A tow conveyor comprising the combination of at least onecarrier, first rails disposed close to the floor, second rails disposedon the first rails in parallel thereto, an engaging means connected tothe carrier pivotally movable in the horizontal and vertical directionsand having rollers in rolling contact with the second rails, at leastone trolley including rollers in rolling contact with the first rails adrive means connected to the trolley to move the trolley along the firstrails, and a pusher mounted on the trolley for engagement with theengaging means and projecting upward from the first rails to connect thecarrier to the trolley and to thereby move the carrier along with thetrolley, wherein the engaging means is positioned in front of thecarrier and a disengaging means is provided in the rear of the carrier,the disengaging means being connected to the carrier pivotally movablein the horizontal and vertical direction and having rollers in rollingcontact with the second rolls, the trolley further including a pushertilting dog mounted thereon in fron of a pusher and projecting upwardfrom the first rails to disengage the pusher from the engaging means bybeing pivotally forced down by the disengaging means of a precedingcarrier and to thereby separate the carrier from the trolley, whereinthe trolley has two parallel pusher tilting dogs spaced apart by adistance greater than the width of an engaging dog disposed at the lowerend of the engaging means and smaller than the width of a tilting platedisposed at the lower end of the disengaging means.
 3. The tow conveyoras set forth in claim 2 wherein a reverse travel preventing dog isinterposed between the two pusher tilting dogs and is tiltably supportedby a pivot and normally remains upright by virtue of weight of itsportion below the pivot.
 4. A tow conveyor comprising the combination ofat least one carrier, first rails disposed close to the floor, secondrails disposed on the first rails in parallel thereto, an engaging meansconnected to the carrier pivotally movable in the horizontal andvertical directions and having rollers in rolling contact with thesecond rails, at least one trolley including rollers in rolling contactwith the first rails, a drive means connected to the trolley to move thetrolley along the first rails, and a pusher mounted on the trolley forengagement with the engaging means and projecting upward from the firstrails to connect the carrier to the trolley and to thereby move thecarrier along with the trolley, wherein the engaging means is positionedin front of the carrier and a disengaging means is provided in the rearof the carrier, the disengaging means being connected to the carrierpivotally movable in the horizontal and vertical directions and havingrollers in rolling contact with the second rails, the trolley furtherincluding a pusher tilting dog mounted thereon in front of a pusher andprojecting upward from the first rails to disengage the pusher from theengaging means by being pivotally forced down by the disengaging meansof a preceding carrier and to thereby separate the carrier from thetrolley, and which includes a fixing means for holding the engagingmeans and the disengaging means to the under face of the carrier,respectively.
 5. The tow conveyor as set forth in claim 4 wherein thefixing means comprises a support member for supporting a rod memberconnecting a running assembly to the carrier pivotally movably invertical directions and a holder secured to the under face of thecarrier to hold the support member slidably.
 6. The tow conveyor as setforth in claim 5 further comprising a loop of endless conveyor lineincluding the first rails and the second rails, a straight conveyor linebranching off the endless conveyor line and including the second rails,and a lift table supporting a rail segment and an engaging member foroperating the support member, the rail segment forming part of thesecond rails in the straight conveyor line and having a lengthcorresponding at least to the length of the running assembly.